Erectile Dysfunction Drugs Can Cause Vision Loss

On Oct.20, 2005, Public Citizen filed a petition with the Food and Drug Administration (FDA) to add black box warnings to the professional product labels, or package inserts, for the erectile dysfunction drugs sildenafil (VIAGRA), tadalafil (CIALIS), and vardenafil (LEVITRA). The warnings would alert prescribers to the possibility of irreversible vision loss with the use of these drugs. The petition also urged the FDA to require that Medication Guides be distributed by pharmacists with each new and refill prescription for these drugs to warn consumers about the possibility of irreversible blindness.

In a study based on reports of blindness in FDA files, we compared the rate of reports of (non-arteritic ischemic optic neuropathy) NAION per million prescriptions filled in those using ED drugs with the rate in those using atorvastatin (LIPITOR) — both groups having presumed increased cardiovascular risk.

For sildenafil, there were 18 times more reports of NAION per million prescriptions than for atorvastatin and, for tadalfil, 25 times more reports. Thus, it is very likely that the drugs can actually cause blindness in some people.

All three of these erectile dysfunction drugs work in a similar manner to inhibit an enzyme known as phosphodiesterase, which plays an important role in vision.

The FDA can request, but not require, that the manufacturer of a drug associated with harm to patients, including death and serious injury, add a black box warning to the drug’s professional product label. This is the strongest type of warning that the FDA can request from a drug manufacturer. However, professional product labels are not routinely distributed to prescription drug consumers, who are left in the dark about the possible harms of the drugs they are prescribed.

The FDA does have the regulatory authority to require a Medication Guide when a drug presents serious risks relative to benefits of which consumers should be made aware. They may do so because this information could affect the decision to use, or to continue to use, the a drug. Sildenafil, tadalafil and vardenafil clearly fall into the category of drugs having serious risks that may affect the decision to use the drug.

This is not the first petition that Public Citizen has filed with the FDA about vision problems with an erectile dysfunction drug. In July 1998, we petitioned the agency to ask that the professional product labeling for the first erectile dysfunction drug on the market, sildenafil, inform prescribers about vision problems with the drug (see Worst Pills, Best Pills News August 1998). Shortly after this petition was filed, a letter was sent to the FDA asking that an advisory committee of outside experts be immediately convened to address vision and other safety problems associated with the use of sildenafil.

In the August 2005 issue of Worst Pills, Best Pills News, we warned readers that sildenafil and the other erectile dysfunction drugs may cause NAION that can result in blindness. NAION is an acronym for Nonarteritic Ischemic Optic Neuropathy. This condition and its association with the erectile dysfunction drugs first came to public attention in May 2005. At that time, the FDA announced that it was in negotiations with sildenafil’s manufacturer, Pfizer Inc. of New York, to include the possibility of vision loss in the drug’s professional product labeling.  

The FDA announcement may have resulted from a study published in the March 2005 issue of the Journal of Neuro-Ophthalmology. The study described seven new cases of NAION associated with the use of sildenafil. Although this study produced the first major public focus on the relation of sildenafil to this disease, there have been 19 cases in the medical literature implicating the erectile dysfunction drugs in the occurrence of NAION published since 2000.  

On June 20, 2005, the editors of the Medical Letter on Drugs and Therapeuticsreported that 14 cases of vision loss associated with use of sildenafil have been published in the medical literature. All of these men experienced NAION with blurred vision, a loss of the ability to see in particular parts of the eye, or both.  

There is now mention of NAION in the professional product labels for sildenafil, tadalafil, and vardenafil. However, these warnings are ambiguous and are buried in the tiny print and written in the dense technical jargon typical of professional labels. Most importantly, this information is rarely seen by consumers unless they ask their pharmacist for the professional product label for the drug they are prescribed. This is the reason that our petition asked that Medication Guides be required to inform the public of the risks of these three erectile dysfunction drugs.

What You Can Do

You should not use sildenafil, vardenafil, or tadalafil for recreational purposes. A recreational purpose is defined as use by men with otherwise normal sexual function who seek to enhance or extend their sexual experience. The possible harm from these drugs, no matter how small, will always outweigh a lack of medical benefit. These drugs should only be used by men with erectile dysfunction who therefore have a legitimate medical need for them. If you experience any visual problems while using these drugs, notify your doctor immediately.